Aircraft rotor wing construction



Nov. 7, 1944. I J. s. PECKER AIRCRAFT ROTOR WING CONSTRUCTION 3Sheets-Sheet 1 Filed July 17, 1943 M 6 H M a 0 J NOV. 7, 1944. v sPECKER 2,362,301

AIRCRAFT ROTOR WING CONSTRUCTION Filed July 17, 1945 3 Sheets-Sheet 2Nov. 7, 1944. J. s. PECKER AIRCRAFT ROTOR WING doNsTRUnon Filed July 17,1943 s Shts-Sheet 5 I H QwMMI stantially on the line 3-4 of PatentedNov. 7, 1944 UNITED STATES PATENT orrlcs AIRCRAFT ROTOR WINGCONSTRUCTION Joseph S. Pecker, Philadelphia, Pa. Application July 17,1943, Serial No. 495,197 17 Claims. (Cl. 244-123) This invention relatesto the construction of a rotor wing for aircraft such as used onhelicopters and autogyros, and the construction may be found to beadapted for use in other wing surfaces and/or control surfaces ofaircraft, ,aL though it is particularly adapted for rotor wingconstruction for aircraft.

Another object of the invention'is to provide an aircraft rotor wingwhich may be partially constructed of plywood or similar material ofsemirigid construction, and which is so braced whereby to secure utmoststrength for weight, particularly inthe direction of the component ofcentrifugal forces applied to the rotor blade during rotation.

A further object of the invention is to provide a rotor blade having ahollow interior in which are located a plurality of tension memberswhich extend substantially throughout the length of the blade, and whichare adjustable in length whereby to compensate for Dre-stressing and forshrinkage, and warping.

An additional object of the invention is to provide a rotor wing theblades of which are of hollow construction, and whereby great strengthfor weight is secured by the provision of longitudinal extending tensionmembers and a spar connector sleeve.

Additional objects will be found hereinafter throughout thespecification, reference being had to the accompanying drawings.

In the drawings:

Figure l is a view in perspective, of anaircraft of the type to whichthe rotor wing construction of this invention is particularly adapted;

Figure 2 is a view in perspective, and partly broken away, of apreferred form of this inven tion;

Figure 3 is a section of the wing tip taken sub- Figure 2; Figure 4 isan enlarged section taken substantially on the line-H of Figure 2;

Figure 5is an enlarged section taken substantially on the line 5-5 ofFigure 2;

Figure 6 is a view similar to Figure 5 but showing a modified wingconstruction according to this invention;

Figure 7 is a fragmentary plan view of plywood Figure 2 partly brokenaway to illustrate the approximate extent of the metal spar andsurrounding molded box spar;

Figure 10 is an enlarged longitudinal section taken substantially on theline Ill-l0 of Figure 9, and broken away for clearness of disclosure;

Figure 11 is a fragmentarysection taken substantially on the line ll-Hof Figure 10, and

the metal stub spar I6 is connected with the molded box spar Ill. Theconnector sleeve I1 is preferably crenelated for ultimate strength forweight in torsion and is made up of pairsof angles I9, 20 which form acontinuous enclosing sleeve for the stub shaft l6 by reason of havingtheir edges welded together at'2l, Figure 4. The sleeve ll is attachedto the metal stub spar iii in suitable known manner, as by welding orbyrivets 22, Figure 4. i

As shown in Figures 2 and 4, this connector sleeve l1 presents twoseparated, elongated flat surfaces 24 to the inner surface of each wallof the rectangular molded box spar l8. These surfaces are secured to theabutting box spar surfaces by bonding, or for instance, by rivets suchas 25, Figure 2. In this manner, the connector sleeve l'l connects themetal stub spar it with the overlying or surrounding portion of themolded box spar l8.

This box spar l8, as shown inFigures 2 and 9, is substantiallycoextensive with the length of the wing tip proper and terminatesadjacent the joint between the wing proper and the wing tip. It ishollow throughout and the outer endis closed by the metal end plate26,'Figures 2, 10 and- 11. The other end of the box spar I8 is securedto the connector sleeve H, as described from which thewing constructionsof this invention are preferably molded, and indicating by arrows thegrain direction in the veneer of the respective plies thereof;

Figure 8 is an enlarged fragmentary section taken at the portion 8-8of-Flg'ureb;

Figure 9 is a plan view of the wing shown in above," and through thesleeve l1 to the metal stub-spar IS. The inner ends of the connectorsleeve l1 and box spar l8 closely engage the inner surface of the innerend wall 21 of the wing proper.

Extending through suitable apertures provid ed in the box spar end plate26 are four tension members 30, 3|, 32 and -33. The outer ends of thesetension members are fixedly securedv to stub spar l6 exthe end plate 26.The four tension members extend throughout the hollow length of the boxspar l8 adjacent its corners and temilnate inwardly in screw portions orscrew threaded portions 34 provided with nuts 35 by means of which theymay be adjusted to stress the box spar l8, and through the box spar I8,the entire wing ii.

The bracket 35 has its cylindrical portion 31 fixed to the metal stubspar It in suitable manner, as by rivets 38, and the flange or footportion 39 thereof is secured in suitable manner, as by rivets 40,. totheinner end wall 21 of the wing proper. Suitable apertures are providedin the flange or foot portion 39 to receive the screw portions or screwthreaded portions 34 of the tension members 30-34.

These tension members 30-34 may comprise wires, rods'or preferablycablesf Where they are in the form of cables, the twist is oppositebetween each pair of adjacent cables as shown in Figures and 6. Thisneutralizes any torsion components in the stressed structure tending tocause warping of the box spar |8 or of the wing proper Hi. If for anyreason, one of the tenslon members is fractured, the remaining tensionmembers effectively maintain the stressed condition in the structuresubstantially unchanged. Likewise, severance of the wing parts will beprevented by the tension members upon occurrence of skin fracture eitherin the box spar or in the skin proper of the wing, by the tensionmembers which will retain the parts in substantial contact. Thus, thespar structure which forms in effect the backbone of the rotor blade,comprises a.

extending throughout a minor portion only of thewing length, acrenelated metal connector sleeve surrounding and 'fixed to the portionof the stub spar within the wing, a laminated tapering box sparextending from the inner end of the wing substantially throughout itslength and surrounding and attached to the connector sleeve, and aplurality of tension members, preferably cables, extending throughoutthe length of the box spar and adjustable in length for pre-stressingand compensating for shrinkage or warping. The stub spar, connectorsleeve, and tension members are all disposed substantiallylongitudinally of the rotor blade or wing, as are the walls of the boxspar, whereby to secure utmost strength for weight in the direction ofmetal stub spar the components of centrifugal forces applied to therotor blade during rotation.

The wing structure surrounding the spar structure or backbone, is ofcellular form with the walls of the cells and the lengthwise dimensionof all cell-forming members disposed longitudinally or axially of therotor blade. As shown in Figures 2, 4 and 5, the nose stringer or nosepiece 4| is laminated with a flat rear surface and curved forwardsurface, the laminations being transverse.

The first longitudinal cell is designated 42 and is formed by the nosestringer 4|, vertical stringer or wall 43, and a pair of stringers inthe form of angles of substantially U-section designated 44 and 45, withtheir legs or side flanges bonded respectively to the rear, flat surfaceof the nose stringer 4| and the forward surface of the wall or stringer43.

The second cell is designated 45 and is formed by the stringer or wall43, the stringer or wall 41 and a pair of stringers or lar to the abovedescribed stringers or angles 44 and 45, and similarly disposed withrespect to their cell, i. e., the legs or side angles are bondedrespectively to the rear surface of the wall 43- stringer or wall 5|, 9.second vertical stringer or wall 53 and a pair of similar oppositelydisposed stringers or angles 54 and I! with their legs or vertical sideflanges bonded respectively to the stringers or walls 5| and 53.

The fourth cell is designated 53 and is formed by the aforementionedstringer or wall-53, the vertical stringer or wall 51 and a pair ofoppositely disposed stringers or angles 58 and 59, with their verticallegs or flanges bonded to the vertical stringer or wallil.

The remaining or rearmost cell 50 is formed by a stringer 0r angle BIand the tailpiece or trailing edge piece or stringer 62. The angle BI isof substantially triangular section with its leg portions or flangesdisposed generally horizontally and the intermediate portion arrangedvertically, in close contact with the stringer or wall 51, and bondedthereto. As shown in Figures-4 and 5, the forward end of the tail piece62 is provided with steps for receiving the ends of the flanges of theangle 6 I which are bonded therein.

The main skin of the wing is formed in halves, the upper half 63terminating forwardly adjacent the mid-portionof the curved forwardsurface of the nose piece or stringer 4|, and terminating rearwardlyadjacent the mid-portion of the curved outer surface of the tail pieceor stringer 62. The lower half 64 of the main skin has its edges inengagement with the edges of the upper half 63. In. order to protect theforward seam at the forward junction of the skin halves 63 and 64, andin order to secure free flow of air over the nose portion of the wing, anose skin, buffer skin, or nose skin covering 65 is provided, whichcovers the nose portions of the skin halves B3 and 64, and the seam attheir junction, and which terminates roughly adjacent the mid-point ofthe box spar l8 both upwardly and downwardly, as shown in Figures 4 and5 of the drawings.

Beyond the outer end of the box spar l8 and the end plate 26, securedthereto, are a pair of oppositely disposed oppositely directed stringersor angles, of substantial U-section, designated 66 and 61, with theirflanges or legs bonded respectively to the longitudinal stringers orwalls 41 and 5| as shown in Figure 1.

As shown in Figures 3 and 12, all of the above described stringers orwalls and angles terminate angles 48 and 49-, simijust short of the endsof the skin 63, 64. The ends of the skin halves 53 and 64 closely engagethe edges of the complementary halves 68 and 69 which form the wing tip.The curved edges of these complementary half skins or tip halves arereceived in steps provided in the tip edge stringer T0 for this purpose.A substantially annular connector 12 underlies the joint ll between theskins of the tip and wing proper, which are bonded thereto as shown inFigures 3 and 12. As shown in Figure 5, apertures 13, I4 and 15 may beprovided for supplying hot air injected in suitable manner into the boxspar 3 into illustrated in Figures the second or intermediate plybuilding up of internal pressure. Like apertures I6, II, I8, I9 and 80provide, when desired, for ventilation and venting of the cells 52 and69 and ill.

In the modification illustrated in Figure 6, the spar structure is of thsame construction as in the embodiment illustrated in Figures 2 to 5,and 9 and 10. The skin is similar, being formed by the skin halves 63and 64 covered adjacent-the leading edge by the buffer skin orprotective skin 66. The wing tip construction is the same as 2 and 12,and is secured to the skin proper 63 and 64 in the same manner. However,the vertical stringers or walls 43, 41, SI, 53 and 51, and the angles44', 45, 49, 49, 64, 58, 59 and 6| are omitted and the trailing edgestringer or tail piece 62 is modified as will hereinafter appear.

In the modified structure a plurality of telescopically arrangedlongitudinal stringers or angles of substantial U-section aresubstituted for the above enumerated stringers and angles, and performthe function performed thereby. Surrounding the oppositely disposedangles 8i and 82 with their flanges abutting substantially at the middleof the upper and lower outer engaged surfaces of the box spar I8, andwith the intermediate portions joining the flanges disposedsubstantially vertically, are a second pair of like, oppositelydisposed, angles 83 and 84, which overlap the aforesaid angles 8i and82, and are bonded thereto, the forward angle 83 having its centralportion complementary with and closely surrounding the forward stringeror nose piece 4| to which it is bonded. Rearwardly of the .angle 84 is asimilar angle 85 of slightly smaller size with its flanges or legsabutting and bonded to the flanges of the angle 84. The trailing edgestringer or tail piece 86 is of reduced size and the outer curvedsurfaces thereof are surrounded by the rearmost angl 81 which has itlegs or flanges engaging and bonded to the legs or flanges of the angle85. The half skins 63 and 84 are bonded to the engaged leg portions orflanges of the angles 8I85, 81 in a manner which will be readilyunderstood.

Optionally, the wing structure shown in Figure 6 may be provided withapertures or vents for the purposes enumerated above. These aperturesmay comprise the apertures 9| in the angle 8| providing communicationbetween the first and second cells, the apertures or vents 92 in-theforward vertical wall of the box spar I8 and providing communicationbetween the second cell and the interior of the box spar. The

aperture 93 in the rearward vertical wall of the box spar may providecommunication between tudinal direction of the wing, and the third orinner ply 90 had its grain direction at 45 degrees from thelongitudinal" direction oraxis on an inclination opposite that 01. thefirst ply or substantially at a right angle to the grain directiontherein.

As shown in Figures 2, 7 and 10, the wood veneer in each layer maycomprise narrow strips cut in the grain direction with their edges gluedor bonded together in a butt-joint to form sheets of substantial width.

While the sheets of three-ply plywood forming the respective skins,stringers, walls and angles have been shown as possessed of substantialthickness, this is an exaggeration made solely in the interest ofclearness and convenience of illustration and disclosure, it beingclearly understood by those skilled in the art that the thickness of theplywood and constituent veneer sheets will vary widely with the strengthof the wood. is also well recognized by those skilled in theart thatextremely thin plywood sheets provide strength amply adequate for thepurpose here intended, and to withstand the forces and stresses to whichthey maybe subjected.

As shown in Figure 12, the wing constructions ustrated in the drawingsand described above, are readily adaptable to jet'drive for the rotorwing. When this is found desirable, the box spar end plate 98, Figure12, is provided with an aperture 99 into which is inserted and rigidlysecured, the inner end of an air-pipe I00, provided at its outer endwitha nozzle IOI disposed at the dethe box spar and the third cell, theapertures 94 I are capable of production from various molded materialseither laminated or otherwise,.a preferred material is illustrated inFigures '7 and 8, and comprises three-ply plywood composed of threelayers or sheets of veneer bonded together. For ultimate strength theplies are arranged so that the grain direction of the first or outer ply88 is substantially 45 degrees from the longitudinalaxis of the wing,spars, stringers and skins, 89 has its grain direction substantiallyparallel with the longisired angle and supported by a transverse rib I02and angular block I03, provided in the wing tip adjacent its outer end.If desired, the air pipe I00 may be rotatably secured in the box sparend plate 98, andsuitable-cont'rols of known type provided for rotatingthe air pipe to vary the angle of the nozzle I III with respect to thewing proper. Compressedair for driving or initiating, rotation of thewing may be injected through the metal stub spar, for instance, into theinterior of the boxspar, whence it flows through air pipe I00 ,andnozzle IIlIv to initiate rotation of the wing or drive the wing. In thisthe box spar l8 and the respective wing cells from which it is sealedoff for obvious reasons.

In Figure 1 is illustrated a rotary wing aircraft of a type to whichblades or rotor wings conularly adapted. As shown, the metal stub sparsI6 carrying blades or rotor wings I5 are rotatably secured in a hub I05,which is rotatably driven by a rotor shaft (not shown), from the engineof the craft (also not shown), which concurrently drives the tailpropeller I06 through which stabilization, guide and control of thecraft is mainly secured. Through linkages including rods II", therespective stub spars I6 are connected with the swash plate I08, which,in-turn, is manually controlled by the pilot through'controls includingthe control rods I 09. positional control of the swash plate, the pitchof the respective blades or rotor wings, and the angle of attack orangle of incidence of the rotor wing'gare controlled as desired.

The craft illustrated in Figure 1 is a helicopter of the closed fuselagetype, comprising a closed fuselage I III with door I I I provided withan openwork boom or tail spar I I 2 for supporting the tail propellerI06 in suitable location with respect to the rotor wing or wing systemI5, I6, l05--I09,

and for supporting the tail propeller drive shaft embodiment, no ventsor apertures are provided between the interior of Through (not shown).It is of course to be understood that the rotor wing constructionsherein illustrated, and above described, are as readily adaptable to alltypes of known rotary wing aircraft, including the free wing or flappingwing type of craft known in the art as autogyros.

Suitable landing gear for operation on land or water is of courseprovided, and may comprise the tricycle landing gear shown, whichcomprises suitable mounted forewheel unit H4 and side wheel units H5suitably located for attainment of ultimate stability and security.

In the specification I have described the skin as being composed ofplywood, but it is to be expressly understood that I may substitute anyother skin material. For instance the several layers shown in Figure 8may be of cloth, which cloth layers may be suitably impregnated with asubstance to give them body. Or I may use one or more layers of plywoodwith other layers of a different material such as cloth.

It will be understood that the above description and accompanyingdrawings are for illustrative purposes only, and that I do not desire tobe limited in the practice of this invention except as defined by theappended claims.

What is claimed is:

1. In a wing blade for rotor wing construction,

a metallic stub spar extending from the hub of said rotor wing, acrenelated spar connector sleeve rigidly mounted on said metallic spar,said sleeve comprising pairs of angles welded together which form asleeve enclosing said shaft, said shaft being of general rectangularconfiguration and having fiat outer surfaces, a molded box sparenclosing said sleeve and lying against the flat surfaces thereof, saidblade having a plate closing one end of said box spar and an end'wallclosing the opposite end of said box spar, four tension memberscomprising cables, diametrically opposite cables being twisted in thesame direction, extending throughout the length of said box spar andlocated between th said spar and said connector sleeve adjacent thecorners thereof.

2.. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a crenelated spar connectorsleeve rigidly mounted on said metallic spar, said sleeve comprisingpairs of angles welded together to form a sleeve enclosing said shaft,said shaft being of general rectangular configuration and having flatouter surfaces, four tension members comprising cables, diametricallyopposite cables extending throughout the length of said connector sleeveadjacent the corners thereof.

3. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a crenelated spar connectorsleeve rigidly mounted on said metallic spar, said sleeve comprisingpairs of angles welded together which form a sleeve enclosing saidshaft, said shaft beingof general rectangular configuration and havingfiat outer surfaces, four tension members comprising cables,diametrically opposite cables being twisted in the same direction,extending throughout the length of said connector sleeve adjacent thecorners thereof, means adjustably connecting the ends of each of saidtension members whereby the stress of each tension member may beindependently adjusted.

4. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a crenelated spar connectorsleeve rigidly mounted on said metallic spar, said sleeve comprisingpairs of angles welded to ether which form a sleeve enclosing saidshaft, said shaft being of general rectangular configuration and havingflat outer surfaces, said blade having a plate closing one end of saidsleeve and an end wall, closing the opposite end of said sleeve, fourtension members comprising cables, diametrically opposite cables beingtwisted in the same direction, extending throughout the length of saidsleeve and located adjacent the corners thereof, means adjustablyconnecting the ends of each of said tension members to said plate andsaid end wall whereby the stress of each tension member may beindependently adjusted.

5. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a crenelated spar connectorsleeve rigidly mounted on said metallic spar, said sleeve comprisingpairs of angles welded together which form a sleeve enclosing said shaftof general rectangular configuration and having flat outer surfaces,said blade having a plate closing one end of said sleeve and an end wallclosing the opposite end of said sleeve, four tension members comprisingcables extending throughout the length of said sleeve and locatedadjacent the corners thereof, means adjustabl connecting the ends ofeach of said tension members to said plate and said end wall whereby thestress of each tension member may be independently adjusted.

6. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a crenelated spar connectorsleeve rigidly mounted on said metallic spar, said sleeve comprisingpairs of angles welded together which form a sleeve enclosing said shaftof general rectangular configuration and havin fiat outer surfaces, saidblade having a plate closing one end of said sleeve and an end wallclosing the opposite end of said sleeve, four tension members comprisingcables extending throughout the length of said sleeve and locatedadjacent the corners thereof.

7. In a wing blade for rotor wing construction,

'a metallic stub spar extending from the hub of 8. In a wing blade forrotor wing construction,

a metallic stub spar extending from the hub of said rotor wing, a sparconnector sleeve rigidly mounted on said metallic spar, said bladehaving a plate closing one end of said sleeve and an end wall closingthe opposite end of said sleeve, and tension members extendinglengthwise of said sleeve and attached to said plate and end wall.

9. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a spar connector sleeverigidly mounted on said spar, said sleeve enclosing said spar and beingof general rectangular configuration and having fiat outer surfaces,said blade having a plate enclosing one end of said sleeve and an endwall enclosing the opposite end of said sleeve.

10. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor Wing, a crenelated shaft connectorsleeve rigidly mounted on said metallic spar, said sleeve enclosing aidmetallic spar and being of general rectangular configuration, meansclosing each end of said box spar, and tension members having their endsconnected to said closing means.

11. In awing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a spar connector sleeverigidly mounted on said metallic spar, said sleeve enclosing saidmetallic spar and being of general rectangular configuration, meansclosing each end of said box spar, and tension-members having their'endsconnected to said closing means.

12. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a spar connector sleeverigidly mounted on said metallic spar, a plurality of tension membersspaced'from each other and extending substantially the length of saidsleeve, and means for attaching said tension members adjacent theopposite ends of said sleeve.

13. In a wing blade for rotor wing construction,

a metallic stub spar extending from .the hub ofsaid rotor wing, a sparconnector sleeve rigidly mounted on said metallic spar, a plurality oftension' members comprising cables spaced from each other and extendingsubstantially the length of said sleeve, and means for attaching saidcables adjacent the opposite ends of said sleeve.

14. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a spar connector sleeverigidly mounted on said metallic spar at spaced points thereon, aplurality of tension members spaced from each other and extendingsubstantially the length of said sleeve, and means for adjustablyattaching said tension-members adjacent the opposite ends of saidsleeve.

15. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a rectangular spar connectorsleeve rigidly mounted on said metallic spar, a

plurality of tension members comprising cables spaced from each otherand extending ssi'bstantially the length of aid sleeve, and means foradjustably attaching said cables adjacent the opposite ends of saidsleeve.

16, In a wing blade for rotor wing construction,

saidblade having a plate enclosing one end of said' box spar and an endwall enclosing the op posite end of said box spar; tension membersextending through the length of said box spar,-

means connecting the ends of each of said tension members to said plateand said end wall, a

plurality of cells extending longitudinally of said blade and locatedon-either side of said box spar, and a skin rigidly attached to'saidcells and box spar.

'17. In a wing blade for rotor wing construction, a metallic stub sparextending from the hub of said rotor wing, a spar connector sleeverigidly mounted on said spar, said sleeve enclosing said shaft andhaving flat outer surfaces, av molded box spar enclosing said sleevelying against the flat surfaces thereof and being attached thereto, saidblade having a plate enclosing one end of said box spar and an end wallenclosing the opposite end,of said box spar, tension members extendingthrough the length of said box spar, means adiustably connecting theends of each of said tension members to said plate and said end

